Process of making metal coated collapsible tubes



June 1943- A. w. WHEELER PROCESS OF MAKING METAL COATED COLLAPSIBLE TUBES Filed April 9, 1940 lll Patented June 1, 1943 PROCESS OF MAKING METAL COATED COLLAPSIBLE TUBES Alexander W. Wheeler, Philadelphia, Pa., assignor to National Lead Company, New York, N. Y., a corporation of New Jersey Application April 9, 1940, Serial No. 328,661

13 Claims.

The invention is a process of making tin-coated lead articles, such as tin-coated collapsible lead tubes, and includes a process of making the intermediate blank and the final product.

Collapsible lead tubes, coated one or both sides with tin, can be made by the usual extrusion process and in quite the same way as ordinary all-tin tubes and because of their small tin content are cheaper and in demand on that account. They are not however suited for all of the uses of the all-tin tube because a small line or band or lead is always left exposed at the neck opening where the lead reacts with the material contained in the tube and discolors or impairs it. By the process of this invention, tubes and other metal-coated articles can be made without such exposed line or band and also, generally, with improved economy.

The successive steps of the process as used for making tin-coated lead tubes and in its preferred form are shown in the drawing, wherein Fig. 1 is a cross section of prepared sheet stock from which the tubes are to be made;

Fig. 2 a section through the dies of the first punching stage of the process;

Fig. 3 a section illustrating the shape at such stage;

Fig. 4 a section at the start of the second stage;

Fig. 5 the same on completion of such stage;

Fig. 6 the extrusion dies and Fig; 7 a section of the shouldered end of the final extruded tube.

The process begins with the preparation of the stock from which the tube is to be extruded and which is a sheet of lead l coated on both faces with coatings of tin 2 and 3. It is produced by rolling or otherwise reducing to sheet or ribbon form an ingot or block of lead having layers of tin on its opposite sides. Preferably the tin layers are cast on the lead while the latter is near its own melting point. This results in what may be termed a fused bond between the tin and lead and is important in securing best results with the thinnest coat, or least amount, of tin. The lead used is preferably an alloy-hardened lead, antimonial for example, having about the same hardness as the tin, although any other metal or alloy could be used as the body metal so far as adapted to this process and the uses of the article. Similarly certain tin-alloys or other surfacing metal might be used in place of pure tin.

The tin-coated lead sheet or ribbon of Fig. 1, thus prepared, is fed to a punch press between upper and lower blocks 4 and 5 and there subjected to the action of upper and lower dies 6 and l, by which the upper face of the sheet is hole in the stock within the countersink. This punch I is dull or rounded as indicated, and so dimensioned with relation to the upper die 6 that as it makes its hole it drags or forces the lower tin coat 3 along with it through the hole or at least far enough into it to meet and form a junction with the tin coat 2a. This extended part of the bottom coat is marked 3a and is long enough so that in the next stage its upper end can be curled over into contact with the upper coat, 2a, thus forming a lining for the hole, completely covering and concealing the edge of body metal therein.

Th punch-slug 9 is caught by the jaws it so that i does not stick to the punch on its return stroke, which might deform the extended part or sharp edge of the coat 312. As will be observed, the punch-slugs pass out through the lateral outlet in the upper die as indicated by the dotted lines, this being usual punch-press design.

At some point in the process, a circular blank must be formed out of the stock, with the perforation at its center, and that is conveniently done in the next punching stage indicated by Fig. 4, wherein the perforated ribbon of Fig. 3 is registered under the punch II, which punches out a circular disc concentric with the hole and at the same time acts on the upstanding edge of the tin coat to to curl or fold it over on to the depressed margin 20. of the upper tin coat. This is no more than the action of an eyelet-setting punch, as will be observed; it folds the normallyexposecl face of the tin coat 3a over into contact with the top or normally-exposed face of the tin coat 2a, thus making a junction between the two coats with a tin-to-tin contact, no lead being exposed. Other forms of junction and other 10- cations of it might be contrived and will sufiice so long as the lead is effectually concealed and sealed up and not likely to escape through the junction under the pressure of the later extrusion. Folding the coats into tin-in-tin contact, as shown forms a self-closing type of seam preventing all escape of lead.

The blank-forming punch II is also shaped and dimensioned with relation to its die cavity I2, like the punch 1, so that as it displaces the disc from the body of the stock, it drags or forces the tin coat 3 over the peripheral edge of the blank, as indicated at 3b, and at the same time dishes the blank to conical form conforming to the shoulder slope of the tube to be made from it. Extending the lower coat around the outer edge of the disc as at 3b is helpful in assuring its uniform flow, with the lead, to form the outer coat on the body wall of the tube. As will be observed, all these operations are readily performed in standard automatic punch presses, which merely require to be equipped with with die tools of the proper configuration.

The extrusion'is done in the usual way, in the die l3, under the impact of the plunger II which first consolidates the junction between the two tin coats (2a and 3a), making a tight seam of them, and then forces that portion of the metal immediately around the hole in the blank, downwardly into the neck cavity i5, and the rest of it upwardly into the crevice it around the plunger to form the shoulder and body of the tube. The tin coatings on the blank follow the lead in this operation, retaining their integrityI as continuous coatings with no lead showing through. The junction between the tin coats occurs in the case in hand, inside the neck of the tube or at the corner between the neck and the shoulder of the tube as shown by Fig. 7, and is thus out of sight, but its particular location is not controlling and as it is not unsightly it could be located outside of the tube according to the preference of the maker or the best die economy.

It will of course be understood that the thickness of the tin coats is shown exaggerated in the drawing for the sake of illustration and that actually it is in the order of electroplate, the thickness of the whole sidewall being in the order of about .008 inch more or less. The coats may be of equal or different thickness or of different surfacing metals and the body wall may be as thin or as thick, and as stiff, as desired.

I claim:

1. The process of making metal-coated articles which includes the step of preparing a body of metal with initially separate adherent coatings of another metal on its opposite faces and then extending bystretching an adherent part of one of said coatings around an edge of the body into contact with each other to conceal the body metal at such edge.

2. The process of making metal-coated articles which includes the step of preparing ,a body of metal with initially separate adherent coatings of another metal on its opposite faces and then 6. The process of making metal-coated ex-. truded articles which comprises preparing a body of metal with coatings of another metal on its opposite faces, forming a hole through the body, countersinking one of the coatings around the edge of the hole, extending the other coating through the hole to a Junction with the countersink and subjecting the body to extrusion pressure to form a coated extruded article.

7. The process of making a metal-coated extruded collapsible tube which comprises preparing a body of metal with initially separate coatings of another metal adherent on its opposite faces, forming a hole through the body, extending by stretching an adherent part of one of said coatings into the hole to make a junction with the other coating and thereby form a lining for the hole, and subjecting the body to the pressure of an extruding plunger to consolidate the Junction and form the blank into a tube of which the metal adjacent the hole forms the neck.

8. The process of the preceding claim 7 in which the coated body is extruded with the iunc tion between the coatings located on the inside of the tube.

9. The process of making tin-coated lead tubes which comprises preparing the stock by reducing to sheet form a billet of lead having a layer of tin fused to each face thereof, forming blanks out of such sheet by means of punch tools which drag the adherent tin coatings thereon over the edge of the blank into contact with each other and extruding the tube from such blank.

10. The process of making tin-coated collapsible lead tubes comprising preparing a sheet of alloy-hardened lead having coats of tin fused to its opposite faces, forming perforated blanks of such sheet by punch tools which drag the adextending by stretching adherent parts of both coatings around an edge of the body into junction with each other to conceal the body metal at such edge.

3. The process of making metal-coated articles which includes the step of preparing a body of metal with initially separate adherent coatings of another metal on its oppositefaces, punching a hole through the body and extending by stretching an adherent part of one of said coatings into I contact with the other through the hole to conceal the body metal in the wall of the hole.

4. The process of making metal-coated articles which includes the step of preparing a body of metal with coatings of another metal on its opposite faces, punching a hole through the body, extending an adherent part of one of said coatings into contactwith the other through the hole and forming a junction between coatings by curling or folding the outer face of one of them over upon the outer face of the other.

5. The process 'of making metal-coated e'xtruded articles which comprises preparing a body of metal with coatings of another metal on its opposite faces initially separate from each other,

herent portions of the opposite tin coats to a Junction with each other through the perforation and which drag the adherent portion of one of the coats around the outer edge of the blank and then extruding the tube from such blank.

11. The process of making a. collapMble-tincoated lead tube which comprises preparing a perforated blank of lead having coatings of tin fuse-bonded to its opposite faces and to the wall of the perforation and connected to each other through the perforation therein and then extruding such blank into a tube so that such coatings cover and conceal the lead in the neck por-' tion as well as the body thereof.

12. The process of making tin-coated lead tubes which comprises preparing a perforated blank of lead alloyed with a hardening agent to make it of about the hardness of the tin, and having coatings of tin fuse-bonded to the opposite faces of the lead blank and to thewall of the perforation and connected to each other through the perforation therein and extruding such coated blank into a tin-coated lead tube.

13. The process of making collapsible lead tubes coated with tin or the like, which comprises preparing a sheet of lead having coatings of tin or the like fused to its opposite faces, perforating such sheetwith a tool which drags the coating on one side through the hole and into proximity to the coating on the other side, forming a junction between such proximate coatings, then punching a blank out of the sheet concentric to such hole and finally extruding the tube from such blank.

ALEXANDER W. WHEELER. 

